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particularly important as sedentarism appears to track among individuals 
from childhood to adulthood (Gordon-Larsen et al., 2004; Nelson et al., 
2006). 
Of interest, a large nationally representative survey found that, “con-
trary to the public perception that media use displaces physical activity, 
those young people who are the heaviest media users report spending 
similar amounts of time exercising or being physically active as other 
young people their age who are not heavy media users” (Rideout et al., 
2010, p. 12). The question was, “Thinking just about yesterday, how 
much time did you spend being physically active or exercising, such as 
playing sports, working out, dancing, running, or another activity?” This 
finding suggests that media use does not displace vigorous- or moderate-
intensity physical activity but more likely displaces light-intensity physical 
activity, schoolwork, and sleep. Light-intensity physical activity, including 
playing or even just standing, is more difficult to measure than vigorous- 
or moderate-intensity physical activity, but its positive health impact is 
increasingly being recognized (see Box 2-4 in Chapter 2). The finding of 
this survey also suggests that promotion of vigorous- or moderate-intensity 
physical activity may not decrease sedentarism but rather might replace 
light-intensity physical activity. Therefore, the optimal way to promote an 
overall increase in physical activity (including light-intensity physical activ-
ity) may be to use behavioral approaches to decrease sedentarism, as has 
been shown in behavioral research (Epstein et al., 1995; Robinson, 1999).
One of the challenges to monitoring sedentarism is the fact that children 
and adolescents frequently multitask. As noted earlier, Rideout and col-
leagues (2010) found that U.S. youth aged 8-18 spent more than 7.5 hours 
per day using recreational media; 29 percent of this time was spent multi-
tasking, resulting in a total media exposure of almost 10.5 hours per day. 
This figure represents an overall increase in sedentarism since 1999, when 
the corresponding figures were 6.2 hours and 7.3 hours per day, respectively. 
Television content still dominated sedentary time, accounting for 4.3 hours 
per day. Computer use for schoolwork (not included in these totals) aver-
aged 16 minutes, while computer use for recreational purposes totaled 1.3 
hours per day. On a typical day, 70 percent of youth went online for any 
purpose, including 57 percent at home, 20 percent at school, and 14 percent 
elsewhere. It is unknown whether all online activities at school were related 
to schoolwork.
In addition to displacing physical activity and schoolwork, recreational 
media use exposes youth to “a constant stream of messages” that shape 
their perception of what is normative, including food choices, physical 
appearance, physical activity, and even sedentarism itself (Rideout et al., 

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Educating the Student Body: Taking Physical Activity and Physical Education to School
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